CalPrex® + MagPrex™ P-recovery

The combination of CalPrex® + MagPrex™ captures 50%+ total phosphorus entering treatment plants, with a minimal addition of chemicals. The CalPrex® process harnesses the acidogenic bacteria power to acidify bio-P sludge. Over 60% of phosphorus solubilizes in the acid phase digestion process. Dewatering acidogenically digested sludge isolates the dissolved phosphorus (orthophosphates), in the centrate. The centrate is sent to the CalPrex® reactor, where orthophosphates are precipitated by calcium hydroxide and calcium chloride. By maintaining a pH solution of 6.5 or below, phosphorus is recovered as brushite (CaHPO4· 2H2O), a market ready, high-quality fertilizer.

MagPrex™  converts the remaining orthophosphates in digested sludge to struvite (MgNH4PO4· 6H2O) by air stripping CO2 and adding magnesium chloride. Struvite is another market ready fertilizer. MagPrex™ reduces the phosphorus recirculation by 90%.